GloMelt Thermal Shift Protein Stability Kit

GloMelt™ dye can be used to detect protein unfolding or measure thermal stability by performing a thermal shift assay, also called Protein Thermal Shift™, differential scanning fluorimetry, or Thermofluor assay.

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Product Description

GloMelt™ dye undergoes fluorescence enhancement upon binding to hydrophobic regions of denatured proteins. Therefore the dye can be used to detect protein unfolding or measure thermal stability by performing a thermal shift assay, also called Protein Thermal Shift™, differential scanning fluorimetry, or Thermofluor assay.

Environmentally sensitive fluorescent dyes can be used to monitor the temperature dependent unfolding of a protein. The protein’s melting temperature (Tm) is a reporter of the protein’s thermal stability.

The thermal shift assay is a rapid and inexpensive technique that quantifies change in protein denaturation temperature, and thus can be used to screen conditions that affect protein thermal stability, such as protein mutations, ligand binding, and buffer formulations (like pH, salts, detergents, and other additives). These assays are rapid (typically about 30 minutes) and are performed on a quantitative PCR system. The thermal shift method is compatible with high throughput screening and requires much less protein than methods such as circular dichroism and differential scanning calorimetry.

Optimize buffer formulation for protein stability and storage

Determine how mutations affect your protein’s stability

Rapidly screen small molecule drug candidates and other ligands for protein binding

GloMelt™ dye has significant advantages over other environmentally sensitive dyes, such as SYPRO® Orange and PROTEOSTAT® TS dye. GloMelt™ dye generates a strong signal because it is optimized for detection in the SYBR® Green channel of qPCR instruments, and therefore low reaction volumes and low protein concentrations can be used. GloMelt™ dye is compatible with high concentrations of protein stabilizers (such as glycerol and sorbitol), and also protein destabilizers (such as DTT and imidazole). GloMelt™ dye performs very well in high detergent concentrations, unlike SYPRO® Orange. Another advantage is that ROX dye can be included with GloMelt™ dye during thermal shift assays, which improves results by increasing replicate consistency in PCR instruments that require ROX passive reference dye.

IgG melt curve plots in the presence of detergent. A thermal shift assay was performed on 20 ug IgG in the presence of 5X SYPRO® Orange or 1X GloMelt™ dye, using a QuantStudio™ 5 qPCR system. The presence of detergent inhibited the SYPRO® Orange assay, but did not significantly affect the GloMelt™ curve.

IgG melt curve plots in the presence of DTT. A thermal shift assay was performed on 25 ug IgG in the presence of 1X PROTEOSTAT® TS dye or 1X GloMelt™ dye, using a QuantStudio™ 5 qPCR system. The presence of DTT drastically reduced the sensitivity of the PROTEOSTAT® assay, but had little affect on the GloMelt™ dye. As expected, DTT reduced IgG thermal stability.

Normalization with ROX reference dye can improve results by increasing replicate consistency. A thermal shift assay was performed on 20 ug IgG in the presence 1X GloMelt™ dye and 50 nM ROX. After ROX normalization the standard deviation was reduced more than 5-fold.

DCDAPH (1,1-dicyano-6-(4-N,N-dimethylaminophenyl)-1,3,5-hexatriene) is a far-red fluorescent probe that has high affinity to Aβ plaques. It has been used for fluorescent staining of brain sections and in vivo small animal near-IR imaging.

Support & Faq

Bioscience kits
The guaranteed shelf life from date of receipt for bioscience kits is listed on the product information sheet. Some kits have an expiration date printed on the kit box label, this is the guaranteed shelf life date calculated from the day that the product shipped from our facility. Kits often are functional for significantly longer than the guaranteed shelf life. If you have an older kit in storage that you wish to use, we recommend performing a small scale positive control experiment to confirm that the kit still works for your application before processing a large number of samples or precious samples.

Antibodies and other conjugates
The guaranteed shelf life from date of receipt for antibodies and conjugates is listed on the product information sheet. Antibodies and other conjugates often are functional for significantly longer than the guaranteed shelf life. If you have an older conjugate in storage that you wish to use, we recommend performing a small scale positive control experiment to confirm that the product still works for your application before processing a large number of samples or precious samples.

For lyophilized antibodies, we recommend reconstituting the antibody with glycerol and antimicrobial preservative like sodium azide for the longest shelf life (note that sodium azide is not compatible with HRP-conjugates).

Chemicals, dyes, and gel stains
Biotium guarantees the stability of chemicals, dyes, and gel stains for at least a year from the date you receive the product. However, the majority of these products are highly stable for many years, as long as they are stored as recommended. Storage conditions can be found on the product information sheet or product safety and data sheet, material safety data sheet, and on the product label. Fluorescent compounds should be protected from light for long term storage.

If you have a Biotium compound that has been in storage for longer than one year that you wish to use, we recommend performing a small scale positive control experiment to confirm that the compound still works for your application before processing a large number of samples or precious samples.

Expiration date based on date of manufacture (DOM)
If your institution requires you to document expiration date based on date of manufacture for reagents, please contact techsupport@biotium.com for assistance.

Ester dyes are stable in solid form as long as they are protected from light and moisture. Esters are not stable in aqueous solution. Concentrated stock solutions should be prepared in anhydrous DMSO (see Biotium catalog no. 90082). Stock solutions in anhydrous DMSO can be stored desiccated at -20°C for one month or longer. Esters should be diluted in aqueous solution immediately before use. Succinimidyl esters (SE) should be dissolved in a solution that is free of amine-containing compounds like Tris, glycine, or protein, which will react with the SE functional group. AM esters and diacetate compounds should be dissolved in a solution that is free of serum, because serum could contain esterases that would hydrolyze the compound.

A note on CF™ dye succinimidyl ester stability
Succinimidyl esters are generally susceptible to hydrolysis, which can result in lower labeling efficiency. Heavily sulfonated dyes, such as the Alexa Fluor® dyes, DyLight® dyes and IRDyes® are particularly hygroscopic, worsening the hydrolysis problem. For example, the percent of active Alexa Fluor® 488 succinimidyl ester (SE) could be well below 50% by the time of application (according to the manufacturer’s product datasheet). In a number of Alexa Fluor® SE reactive dyes, the SE group is derived from an aromatic carboxylic acid, while in all of Biotium’s CF™ dyes the SE group is prepared from an aliphatic carboxylic acid. This structural difference reduces the susceptibility of CF™ dye SE reactive groups to hydrolysis, resulting in relatively stable reactive dyes with consistently higher labeling efficiency compared to other SE derivatives of other fluorescent dyes.

Maleimides, MTS and thiosulfate dyes
Like the succinimidyl ester dyes, these dyes are also susceptible to hydrolysis, although generally to a much lower degree. Thus, for long term storage, anhydrous DMSO is recommended for making stock solutions.

Other reactive dyes
Amines, aminooxy (also known as oxylamine), hydrazide, azide, alkyne, BCN, and tyramide reactive dyes, as well as dye free acids, are generally stable in aqueous solution when stored at -20°C for 6-12 months or longer, as long as no compounds are present that may react with the dye’s functional group. See the product information sheets for specific reactive dyes more information.

Coelenterazines and D-luciferin

Coelenterazines are stable in solid form when stored as recommended; they are not stable in aqueous solution. Concentrated coelenterazine stock solutions (typically 1-100 mg/mL) should be prepared in ethanol or methanol; do not use DMSO or DMF to dissolve coelenterazines, because these solvents will oxidize the compounds. Ethanol or methanol stocks of coelenterazine can be stored at -20°C or below for six months or longer; alcohol stocks may evaporate during storage, so use tightly sealing screw cap vials and wrap the vials with Parafilm for long term storage. Propylene glycol also can be used as a solvent to minimize evaporation. If the solvent evaporates, the coelenterazine will still be present in the vial, so note the volume in the vial prior to storage so that you can adjust the solvent volume to correct for evaporation if needed. Prepare working solutions in aqueous buffers immediately before use. Coelenterazines are stable for up to five hours in aqueous solution.

Aquaphile™ coelenterazines are water soluble formulations of coelenterazines. They are stable in solid form when stored as recommended. Aquaphile™ coelenterazines should be dissolved in aqueous solution immediately before use. They are stable for up to five hours in aqueous solution.

Note that coelenterazines are predominantly yellow solids, but may contain dark red or brown flecks. This does not affect product stability or performance. If your coelenterazine is uniformly brown, then it is oxidized and needs to be replaced.

D-luciferin is stable in solid form and as a concentrated stock solution when stored as recommended; it is not stable at dilute working concentrations in aqueous solution. Prepare concentrated D-luciferin stock solutions (typically 1-100 mg/mL) in water, and store in aliquots at -20°C or below for six months or longer. Prepare working solutions immediately before use.

Many of our solid compounds are packaged by lyophilization, in which case they usually do not appear as fluffy powders, but form a film or coating on the sides of the vial. Simply add the appropriate volume of the recommended solvent to the vial to make the desired concentration stock solution, and swirl or gently vortex to mix. Make sure the solvent comes in contact with the inside walls of the vial to fully recover the product.

Most of our products are stable at room temperature for many days, but we recommend storage at 4°C or -20°C to prolong shelf life. In the case of many of our aqueous dye solutions, the compounds are very stable at room temperature, but we recommend cold storage to prevent the growth of mold or other microbes over time. Therefore, to save on shipping costs, products with recommended storage at 4°C or -20°C may ship at ambient temperature without affecting product performance. When you receive the product, place it under the recommended storage conditions.

Shipping/Shelf-life

Shipment Method: Shipping and handling methods will be assessed and calculated at time of shipment based upon item(s) storage temperature conditions.
Expedited shipment may be requested at time of checkout.
Please note that products with recommended storage at 4°C or -20°C may ship at ambient temperature. This will not affect product performance. When you receive the product, place it under the recommended storage conditions.